Stretchable Piezoelectric Power Generators Based on ZnO Thin Films on Elastic Substrates

Abstract

The paper describes a stretchable, microfabricated power generator that will be attached on the skin and will produce energy based on the movements of the human body. The device was fabricated on a polymeric, elastomeric, poly(dimethylsiloxane) (PDMS) sheet. It consists of a piezoelectric thin film of ZnO sandwiched between two stretchable gold electrodes. An innovative technique was used for the deposition of ZnO thin film on the gold electrode-coated polymeric substrate at low temperatures below 150 °C. This is the first attempt to use a uniform film of ZnO, for energy harvesting. The ZnO film had the thickness at the submicron scale and the surface at the centimeter scale. We demonstrated that under a strain of 8% the voltage output from this power generator was equal to 2 V, the power output was equal to 160 μW and the corresponding power density was 1.27 mW/cm2. This device has great potential for application in power sensors attached on the human body, such as temperature sensors or wearable electrocardiography systems.

Wide-Band-Gap Semiconductors for Biointegrated Electronics: Recent Advances and Future Directions

“…Each material family offers unique electrical, optical and chemical characteristics that can be utilised for sensing and recording function, Table 2. (42) • Sensitive mechanical sensing (43) • Wearable Ultraviolet (UV) photosensor (44) • Transient energy scavenger (21), (37) III-nitride…”

“…73,75−78 The significant piezoelectric effect in ZnO nanothin film and nanowires combined with low-temperature synthesis and/or the capability of a role-to-role transfer process enabled the development of nano energy generators (i.e., nanogenerators) that provide the operating power for wearable and implantable devices (Figure 2a). 21,37,69,79 Depending on applications, the ZnO nanowires can also be structured into different configurations such as lateral and vertical arrays 80−82 to enhance the output current and voltage. Furthermore, while ZnO nanowires were reported to have similar Young's modulus with their bulk and thin film of around 144 GPa, they possess up to 40 times larger ultimate strengths compared with bulk ZnO.…”

“…• wearable ultraviolet (UV) photosensor 44 • biodegradability 37 • transient energy scavenger 21,37 • biocompatibility 38 III−nitride • direct band gap 45,46 • bottom-up growth combining with transferring flexible substrates 53 • sensitive mechanical sensing 53 • high optical transmittance 47,48 • top-down micro/nanomachining combining with transfer printing 54 • wearable ultraviolet photosensor 55 • piezoelectric polarization 49 • long-term energy scavenger 49,56 • high electron mobility 50 • radio frequency wireless communication devices 57,58 • long-term stability 51 • optogenetics LED 59 • biocompatibility 51,52 SiC…”

“…Commonly used wide-band-gap materials and their applications. Figure reproduced with permission from refs − . Reproduced from ref .…”

Graphene/Silver Nanowires/Graphene Sandwich Composite for Stretchable Transparent Electrodes and Its Fracture Mechanism

“…Indium-doped tin oxide (ITO), which exhibits excellent physical properties, such as high transmittance (light penetration of over 80%) and very low sheet resistance (<30 Ω/□), is extensively employed in the electronics industry. Currently, with the advent of flexible and wearable electronic devices [ 5 ], TCFs are expected to exhibit flexibility, high conductivity, stability, and portability. The flexibility and stretchability of the TCFs would be critical due to its applicable applications, including human microchip implants, smart clothes, and smart portable devices.…”